Automatic control device for gearboxes



NOV. 3, 1959 PERAS 2,910,884

AUTOMATIC CONTROL DEVICE FOR GEARBOXES Filed July 25, 1956 2Sheets-Sheet l Nov. 3, 1959 Filed July 25, 1956 L. PERAS AUTOMATICCONTROL DEVICE FOR GEARBOXES 2 Sheets-Sheet 2 United States Patent MAUTOMATIC CONTROL DEVICE FOR GEARBOXES Lucien Pras, Billancourt, France,assignor to Regie Natiouale des Usines Renault, Billaucourt, France,French works Application July 25, 1956, Serial No. 599,971 Claimspriority, application France August 11, 1955 8 Claims. (Cl. 74-472) Thepatent application Serial No. 500,976 of April 12, 1955, in the name ofthe present applicant, described an automatic control device forgearboxes, more particularly for vehicles, of the type in which thepassage from one gear ratio to another is effected under the influenceof the speed of rotation of a shaft, characterized in that it. comprisesat least one system of contactsconnected to a suitable electrical sourceand actuated by the said shaft, in such a manner as to supply anexternal circuit comprising the coil of one or more relays, andpreferably a condenser, with a pulsating current whose average intensityis a function of the speed of the shaft, the purpose of the said currentbeing to engage the relay or relays at a predetermined speed.

The present application relates to a control device which is improved asregards the method of producing the pulsating current and thedetermination of the point of operation of the control relay. The saidpoint being determined independently of the voltage of the battery andthe temperature of the relay coils. According to the invention, at leastone impulse-generating condenser is arranged on a rotor driven by theshaft whose rotational speed is to influence the change-over from onetransmis sion ratio to the other. The rotor is constructed as a bar-typecommutator through whose bars the condenser is charged and discharged.Furthermore, gear changing may be controlled by a double-coil relay.

Several forms of embodiment of the improved device according to theinvention will now be described, by way of non-limitative example, withreference to the accompanying drawings, wherein:

Figs, 1 to 3 are schematic circuit diagrams and illustratediagrammatically three methods of arranging condensers on the rotor;

Fig. 4 is a general diagrammatic view of the device provided with thedouble-coil relay.

Fig. 5 is a perspective view illustrative of an overall arrangement ofthe present invention in a vehicle.

It should be noted that in the following description, those parts whichare common to the various embodiments have been giventhe same referencenumerals. Moreover, it will be understood that the present invention isdescribed with respect to an automatic control device for gear boxes(not shown) in vehicles of the type in which the change of one gearratio to another is effected as the function of the speed of an outputshaft of the gear box as later herein described.

The device illustrated diagrammatically in Fig. lis provided with acondenser 10 arranged on a rotor 1, which is constructed as a bar-typecommutator as shown, and which is driven by an output shaft, not shown,of a gear box 30, whose speed variations are to influence the system.The different bars of the commutator are connected 2,910,884 PatentedNov. 3, 1959 2 to one of the armatures of the condenser 10 which rotateswith the commutator, the other armature being connected to ground bymeans of a shaft 1a and the bearings thereof, with or without the use ofa contact, for example, a sliding contact 1b. A brush 3 is connected toan electrical source 5, and a brush 4 is connected to a relay 6. Thedimensions and number of the commutator bars, the dead spaces separatingthem, and the angle which the brushes 3 or 4 form between them, are suchthat the cycles of charging and discharging the condenser succeed oneanother without its being possible for current to pass directly betweenthe brushes 3 and 4.

The condenser 10, one side of which is constantly connected to ground,is charged at the voltage of the electrical source 5 each time that oneof the bars of the commutator to which the other armature of the saidcondenser is connected, comes into contact with the brush 3, and isdischarged into the circuit of the relay 6 each time that a bar comesinto contact with the brush 4, thus producing in the said circuit apulsating current which, when its mean intensity reaches a predeterminedvalue, causes the relay 6 to engage. A blade 7 is attracted and thecontact 8 closed, so that an operating winding of an apparatus 9, forchanging gear ratios in the gear box 30, in known manner has currentsupplied thereto. A rheostat 11, connected to an accelerator 37 for thevehicle, allows a variable fraction of this current to be diverted, andthus to alter, as a function of load, the main current flowing in thewinding 6 and consequently the speed at which the relay pulls in andcauses a change of gear ratios.

In the device according to Fig. 2 of the accompanying drawings, thecondenser 10 is also fast with the rotor 1 which has the form of acommutator having an equal number of bars (six in the case of thisfigure). In this embodiment, the two sides of the condenser 10 areconnected respectively to two series of alternate bars. The bars areseparated by non-conductive spaces. These nonconductive spaces and thewidth of the brushes are so dimensioned that each brush can only come incontact with one bar at a time. When the rotor 1 has rotated throughsuch an angle that the following pair of bars is in contact with thebrushes 3 and 4 respectively, the condenser armature previouslyconnected to the brush 4 is now connected to the brush 3, and viceversa, and the charge voltage of the condenser is added to that of theelectrical source, sending through the circuit of the relay 6 an impulseof greater energy than in the preceding case where only the voltage ofthe source was used. The other circuit members of the device areillustrated as arranged in the manner of Fig. 1 except that a condenser12 is connected in parallel with the rheostat 11.

Fig. 3 illustrates a device wherein condensers such as 10 and 10", twocondensers in the case of this figure, are carried by the rotor 1, whichhas the form of a commutator having twice as many bars as there arecondensers (four bars in the case of this figure), the sides of each ofthe condensers are connected respectively to two opposite bars. Thisarrangement makes it possible to reduce the dead space between twoconsecutive bars to the smallest possible amount compatible with theirinsulation. It is possible in this case for the brushes to be in contactat the same time with two consecutive bars.

Each of the condensers 10 and 10 is charged when the two commutator barsconnected to its armatures are respectively. in contact with the brushes3 and 4, and is 3 discharged when this same pair of bars again comes incontact with the two brushes in the inverse position, the condensercharge voltage being added to that of the electrical source as in thepreceding case. It being understood that the rest of the circuitelements are connected similarly to the embodiment in Fig. 1.

Fig. 4 concerns a form of embodiment in which the core of theelectromagnet of the relay carries not only a coil 6 which is suppliedby the pulsating current proportional to the speed of the shaft 1a, butalso, accord ing to a well-known method, a coil 16 in opposition withthe first coil. It is in the circuit of this coil 16, fed by the sameelectrical source (batteries) as the rest of the device, that therheostat or rheostats such as 11 can be provided. The rheostat 11 isintended, for example, to cause the engine load factor to act upon thepoint at which the relay is engaged.

The attraction force acting on the blade 7 will be a function, apartfrom one constant, of the relative fluxes produced by the coils 6 and13. The fact that these coils, wound on the same core, are traversed bycurrents proportional to the voltage of one and the same source, has theadvantage of making the point of operation of the relay largelyindependent of the voltage of the battery and of the ambient temperatureof the coils.

As shown in Fig. 5, the invention is easily mounted in a vehicle. Thusthe make-break switch is mounted adjacent the output shaft of the gearbox and the relay 6 and its associated condensers are mounted in anenclosure 31 and the variable resistance 11 is in an enclosure 32. Alink 33 connects the resistance 11 with the throttle control links 35connected to the vehicle accelerator 37. The battery 5' is connected tothe various elements, as shown, for operably controlling device 9actuating the gear box 30.

While preferred embodiments of the invention have been shown anddescribed it will be understood that many modifications and changes canbe made within the scope of the invention.

I claim:

1. In combination with a power transmission system having an automaticchange-speed gear box provided with means for changing gear ratios and adriven output shaft, arotor shaft operatively driven by said outputshaft at a speed corresponding to the speed of the output shaft andprovided with angularly spaced, peripheral, conductive portions,aspeed-respons-ive control circuit operatively connected to said rotorshaft comprising a source of direct current, first electro responsivemeans for actuating said means for changing gear ratios, normally openelectrical connections between the source of direct current and thefirst electro-respons-ive means, second electro-responsive means forclosing said connections at selected mean current values of pulsatingcurrent and holding them closed while said current values obtain, the

current values corresponding to selected rotational speeds of the gearbox output shaft, at least one capacitor mounted to rotate with saidrotor shaft and connected to the rotor shaft conductive portions, afirst contact means connected to the source of direct current and asecond contact means connected to the second currentresponsive means,said contact means being arranged to successively make electricalcontact with said conductive portions as said. rotor shaft rotates,whereby said capacitor is successively charged and then discharged tosaid second current-responsive means thereby to energize it withpulsating current.

2. Incombination with a power transmission system having an automaticchangespeed gear box provided with means for'changing gear ratios and adriven output shaft, a rotor shaft operatively driven by said outputshaft at a speed corresponding to' the rotational speed of the outputshaft and. provided with angularly spaced, peripheral, conductive barmembers, a. speed-responsive control circuit operatively connected tosaid o r s a t co p si g a source of direct current, firstelectro-responsive means for actuating said means for changing gearratios, normally open electrical connections between the source ofdirect current and the first e-lectro-responsive means, secondelcctro-responsive means for closing said connections at selected meancurrent values of pulsating current and holding them closed while saidcurrent values obtain, the current values corresponding to selectedrotational speeds of the gear box output shaft, at least one capacitormounted to rotate with said rotor shaft and connected to the rotor shaftconductive bar members, a first contact means connected to the source ofdirect current and a second contact means connected to the secondcurrentrespon'sive means, said contact means being arranged tosuccessively make electrical contact with the conductive bar members assaid rotor shaft rotates, whereby said capacitor is successively chargedand then discharged to said second current-responsive means thereby toenergize it with pulsating current.

3. The combination according to claim 2, including connections betweenthe conductive bar members arranged for allowing ener'gization of thesecond current-responsive means from the capacitor and the directcurrent source and-arranged so that the discharges of the capacitor correspond in timing with current pulses from the direct current sourcethereby to make the direct current pulses and the discharge currentsadditive.

4. The combination according to claim 2, including least a secondcapacitor, each of said capacitors being connected to an individual pairof diametrically opposed conductive bar members, and in which said firstand sec= ond contact means are arranged to make electrical con tact withtwo successive conductive bar members simultaneously thereby to energizethe second current-responsive means with pulsating direct current fromthe direct current source and simultaneously synchronizingthe. capacitordischarges with the current pulses, from. said direct current source andmaking the direct current pulses and discharge currents additive.

5. The combination according to claim 2, in which said secondcurrent-responsive means comprises a relay having a first coil connectedto said first contact means and a second coil connected to the secondcontact means, said coils having turns wound in opposition and both connected in parallel to said direct current source.

6; The combination according to claim 5, in which the power transmissionsystem includes a variable speed prime mover and an accelerator forvarying the speed of the prime mover and in which the control circuitincludes variable impedance means in series with said first coil forvarying. the pulsating current energiz ing said secondcurrent-responsive means as a functionof the actuation of theaccelerator of said prime mover, and means opera'bly connecting saidvariable impedance means to said accelerator.

7.- The combination according to claim 2, in which said secondcurrent-responsive means comprises a plurality of flux generatingactuating coils arranged for rendering. the second current-responsivemeans responsive substantially independent of the voltage of said directcurrent source and the ambient temperature of the coils.-

8, In combination with a power transmission system having: an automaticchange-speed gear box provided with means for changing gear ratios and adriven output shaft, a rotor shaft operatively driven by said outputshaft at a corresponding speed and provid'ed with angularly spaced,peripheral", conductive bar members, a speed-responsive control circuitoperatively connected to said rotor shaft comprising. a source of directcurrent, first electro-resp'onsive means for actuating said means forchanging gear ratios, second electro-responsive means for controlling:saidfirst electro-responsive means as a function of selccted-rneancurrent values of pulsating current and holding. them closed Whilesaidcurrent values obtain, the cur-- rent values corresponding toselected rotational speeds of the gear box output shaft, at least onecapacitor mounted said second current-responsive means thereby toenergize to rotate with said shaft and connected to the rotor shaft itwith pulsating current. conductive bar members, a first contactconnected to the source of direct current and a second contact connectedReferences C'ted m the file of this Patent to the secondcurrent-responsive means, each contact ar- 5 UNITED STATES PATENTSranged to successively make contact with the conductive 2,063,701Seyfert Dec. 8, 1936 bar members as said rotor shaft rotates, wherebysaid 2,530,749 Yardeny Nov. 21, 1950 condenser is successively chargedand then discharged to 2,630,970 Cradduck Mar. 10, 1953

